This invention relates to insulation panels in general, and more particularly, to an improved insulation panel particularly useful for application to boiler walls, precipitator walls, ducts, tanks and other types of equipment requiring insulation.
Due to the energy shortage and high costs of energy, insulation of various types of equipment for purposes of heat conservation is becoming increasingly important. Together with the requirements for greater amounts of insulation, the costs of insulation has also risen. These costs have resulted from a greater demand for insulation caused by the fuel shortage and generally inflated construction costs. Because of this, it is important that any insulation system be capable of installation at low cost, giving good thermal efficiency and having a long service life. Furthermore, it should have a pleasant aesthetic appearance.
Prior art systems do not fulfill all of these requirements. An example of such a prior art system is that disclosed in U.S. Pat. No. 3,961,454. Disclosed is a prefabricated insulation panel which has a face member of imperforate sheet material with a top flange and an upright attaching flange at the rear thereof. It also includes an inside foot flange, spaced above the bottom edge of the face member, defining a lapping bottom portion. Insulation material is received and retained against the inside of the face member between the top flange and the foot flange. This type of construction aids in pointing out the number of disadvantages of prior art systems. When attached to a structure, the attaching flange uses a plurality of appropriate sheet metal screws, or the like, inserted therethrough. In this manner, the whole of the flange comes into contact with the structure being insulated and can result in increased heat loss through conductivity. Furthermore, appropriate holes must be made at proper mounting locations for insertion of the screws. This raises installation costs. Furthermore, because the face member is made of a sheet material, it lacks a certain amount of dimensional stability and tolerances cannot be held. Furthermore, when such panels are subjected to wide temperature changes, problems can result because of thermal expansion. It has been typical in insulating panels, to use such a bent sheet or rolled sheet, to form panels and thus most systems suffer from these disadvantages. The panels of this patent do attain a certain amount of simplicity in construction by the utilization of the foot flange and mounting flange to obtain overlapping. However, at the point of overlap there is a large metal area which permits the transmission of heat by conduction. In addition, mounting is difficult.
There have been some attempts to ease the problems of mounting insulation, and permit better interlocking in associated areas. An example is U.S. Pat. No. 3,618,281 which utilizes interfitting panels having tongue and grooved connections. The disclosed panel is for use in a wall type panel rather than an insulating device. In U.S. Pat. No. 2,989,157 sliding chips are used for mounting the insulation. However, there is a requirement for a die clinching operation. Thus, although it has the ability to move the insulating mounting means, which aids to a great degree in installation, since holes need not be drilled at appropriate locations, which locations may differ from installation to installation, it suffers from other problems, i.e., it requires a die clinch. Furthermore, it utilizes a sheet type material and thus suffers from the above-noted disadvantages. Another type of insulating panel is that shown in U.S. Pat. No. 3,372,520. The described panel is a complete insulated panel in which the insulating material is contained within an outer skin and inner skin. The units fit together in a tongue and groove attachment, with the panels themselves attached to stringers by means of fastening members rotatable on the stringer. The manner in which the fastening members cooperate with the panels permits attaching to the panels at any location along its length. Panels of this nature, are not particularly well adapated for use in the insulation of ducts, boilers, precipitators etc. Furthermore, they do present a large path for heat conduction and also are made using sheet metal materials, which suffer the above-noted disadvantages.
In view of the needs outlined above and the lack of the prior art to fill these needs, the requirement for an improved insulating panel is evident.